RIVAS-IRIARTE EXPEDITION. The second Spanish coastal voyage to search for the Sieur de La Salle's Texas colony, the Rivas-Iriarte expedition, was also the most important. It found the wreckage of La Salle's ships at Matagorda Bay and made a complete circuit of the Gulf of Mexico. The circumnavigation provided the basis for a detailed diary by the chief pilot, Juan Enríquez Barroto, and his coastal map, which has not yet come to light. The voyage was made in two piraguas (small, open vessels equipped with oars and a single sail) built at Veracruz especially for the purpose. The two craft, named Nuestra Señora del Rosario and Nuestra Señora de la Esperanza, had keels of fifty-four and sixty feet and were of shallow draft. Rosario, commanded by Martín de Rivas, was the larger. Esperanza was captained by Pedro de Iriarte. The ships were designed on the recommendations of the two chief pilots, Enríquez Barroto and Antonio Romero, who had conducted the first search voyage early in 1686, from Havana to the Mississippi River. Each had twenty oars per side, carried provisions for 3 ½ months, and towed canoes for exploring in shallow water. Manned with sixty-five soldiers and sailors, each vessel was mounted with six bronze swivel guns.
Full article on the Texas State Historical Association's Handbook of Texas Online